The first three letters in diet spell die. Yes a diet may halp u lose weight but once u go off of the diet u will gain it back. The best thing is to change your eating habits and lifestyle. Check with your dr he could send u to a dietician. However here's what I did (with the supervision of dietician). (I have lost over 150lbs in about 10 mnths). I started by increasing my activity level. It's hard when your this much over weight but it's possible. I started with a simple beginners yoga routine that I bought a cd of. I did that every morning. Instead of taking the elevator in buildings I used the stairs to go down. When I first started I could not go up stairs easily so I did use the elevator for that but I don't anymore. And I started with a 10 min walk every day and am now up to about a 45min walk. I consulted with a dietician and she helped come up with an eating plan that worked for me. I use a protien shake for breakfast and lunch and have a small snack in the morning afternoon and before bed. I also have a small well balanced meal for supper. I switched from drinking pop to diet pop and flavored water and drink a fair amount during the day it helps u feel full. Once a week I allow myself a treat for following my eating and excercise plan that way I don't build up big cravings and break down and binge on junk food. This has been working for me I still have another about 175lbs I need ti lose. B sure to check with your dr b/c part of your weight problem could b a medical issue like thyroid or something and unless something like that is treated it will make it much harder Good luck hope this helps
I recommend a slow carb diet, try the one outlined in the book "The 4 Hour Body" by Tim Ferris. It combines the fat burning power of a ketogenic diet with just enough slow digesting carbs to keep you energetic and satisfied.
If you are 200 pounds overweight you have some lifestyle and eating habits to change . Don't try to do it by yourself. Start with your family doctor who can help you and get you in touch with people to help with these changes.